No fiscal solution could fix San Francisco housing prices, only 'fix' would be crushing Silicon Valley so it ceases to be attractive place to be.
If renting is a problem you are doing something wrong. Median gross rent in U.S. is $959 a month. That doesn't sound much for developed country to me. Buying real estate is accessible to majority of U.S. households, in fact almost every dual income household. 63.7% have it, and many who don't have it, just don't want it (for example, i am making what it takes to buy an apartment i am living in, in 8-9 months, but i am not buying because i am not a gambler). To me not buying real estate seems a rational choice, unless you have a very 'fixed' career - like, certain that you are going to stay in a place for decades. There are fewer and fewer people like that, labor market gets a lot more fluid.
Why not? We are born onto the earth, and yet under the current system it is already owned by someone else, and we have to slave to those owners just to "earn" a place to be. IMHO We are each entitled to a share of nature as a birthright, and a way to achieve that while still allowing "ownership" or exclusive access to land is to apply a 100% tax. Should one be able to own the air? Or the world's water? It's not far different to land ownership.
By "afford housing" I don't mean just buying, but also renting. Rent prices reflect sale prices.